Ok, after speaking with Roy, he has me back on my original thought of fuel starvation. That dude is a wiz, and although it may not be the answer, I;m spending a few sheckles on a rebuild kit for the lift pump before I break any GPs!

Not until after my visit to Reading England unfortunately.

I just finished a bunch of top end work on my 606.912. Changed the head gasket, new glow plugs, rebuilt injectors, cleaned the intake, etc. Lots of stuff.

So engine started fine in cold weather after all that work, but it was nailing a bit at idle. Rev the engine up and it smooths out and runs fine. Let it drop back down to idle and the nailing begins again.

I ran a can of Diesel Purge through, and that reduced the nailing a bit, but it was still present. Next I went out and did an "Italian Tune-up". Nailing is GONE!!! Starts up on a 30 degree morning now and just purrrrrs. Yay!

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'98 E300 turbodiesel

Hey guys. I'm having the same nailing problem. Runs fine but nails at idle. My lines are still sucking air from somewhere around the prefilter.

My question is this. Has anyone had the guts to try to eliminate the prefilter and its asinine housing from the equation altogether? I picked up some rubber hose and a good old fashioned prefilter specified for the OM616 engine. I also picked up some backup fuel lines for the prefilter-SOV and the fuel heater/prefilter connections. I plan to simply cut the existing lines, slip the hose over the plastic lines and clamp in place. Then I will put the inline clear prefilter in place of the stock prefilter. I'm going to see if this helps with the leaky lines.

Any ideas?

You're going ot have to route the fuel from the pre-heater to the SOV and then figure out a way to plug the entry and exit from the prefilter.

Would be lots easier to just replace the pre-filter and big oring. If you are having trouble sealing it try crimping the washer to create more downward pressure on the fuel line/prefilter assembly and also lube the prefilter oring and fuel line oring with a small amount of silicone grease.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

I was able to get the prefilter sealed, I even tested it with a Mity-Vac and had no leaks. It would still suck bubbles down into the SOV. I tried replacing the prefilter, with an old style prefilter.

The problem with air in the line from the prefilter to the SOV is that the lift pump will suck air from the upper end of the prefilter down the tube. This occurs in both the instance of the "stock" prefilter and the "modded" prefilter. Looks like I will be taking the IM off once again (third time this year) to test each component for vacuum leaks.

I like this car when it runs right.... which at this point is about 3 months out of the year. Sheesh, I should have bought a MG if I wanted to work on the car this much.

Its possible to get a bad prefilter. Replace it.

If there is air in the line from the bottom of the prefilter to the SOV, then the leak precedes that point.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Well, with a fuel system that is 100%, the condition ios worse then ever. Now it doesnt even run right when it warms up, and so much smoke its damn embarrassing.

Flippin' compression engine. Give it better fuel psi, and it craps out.

Back to either breaking a GP doing a compression test, or just R&R the IP for a bench test.

What was the result of the compression test?

I had very similair problems and had several specialist look and check and thought injector, then prechamber, then compression ck (one low cyl)

Then they thought blow head gasket and stuck rings or a valve seat loose.

Well as I thought all along "bent connecting rod"

This was my bro- in laws car before and he drove it knocking for years and hundred + thousand miles.

Only pulled the motor up high enough to slip the pan off. Fellow did the job in 2 days.

It nailed like a barrell of monkey's with hammers banging then would seem to run ok then.

Now she runs like a singer sewing machine.

Keep looking but check that compression.

Yeah, I get the break some gp s to test compression. Need to find a better injector side adapter.

what does it mean to 'nail at idle'?

A car I was looking at had the same issues of fuel stavation but not at idle.
It turns out it was a bad fuel line.

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Ginny in Denver-ish
78 300SD, 265K (mine)

Nailing is a "clackity" type sound that is "normal" with some engines at idle, and not so normal with other engines at idle. If it were a gas engine, it would sound like a minor crankshaft or connecting rod bearing knock. The 606 engine usually a very quiet engine that is free of any "clackity" sounds at idle, so it may be an issue that needs to be looked at.

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96 E300d

thanks!

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Ginny in Denver-ish
78 300SD, 265K (mine)

"What in Heaven's name would cause the engine to start very well, run excellently, and then deterorate into a smokey clanking mess?

Why does it run better, longer, after sitting for a long time?

Bought a compression testor, as the fella would rebuilt the INJs said it was likely poor compression in a cylinder or possibly a bad prechamber.

But it starts mint, and runs like new for a little bit. Bad compression would be noticeable right at start up and would go away as the heat of the enigne sealed the cyl better? yes?"

I know that this might not apply to your problem, but I have a 96 e300d that had a delivery valve leak. Up to this point, the engine was as quiet as a mouse at idle and under power with no smoke. I researched the forum in order to make the necessary repairs. Some posters indicated that it was not necessary to change the crush washers when changing the seals, and I did the repair by just changing the rubber seals. I did all six delivery valves, and then started her up. For about 60-90 seconds, the engine was as quiet as it was prior to the repair, but then it started nailing at idle, which it never did before. It was fine under power, with no smoke issues. I have a scangauge attached to the car reading voltage, and I noticed that the engine was totally quiet when started cold, and would start to clatter as soon as the afterglow cycle disengaged. I drove it that way for about 400 miles with no improvement, and then decided to redo the delivery valves, only this time using new crush washers and seals. Finished the repair, fired her up, and the nailing at idle was totally gone. My thought is, that the nailing at idle was due to excess fuel being injected into the engine because of my failure to change out the crush washers when I first made the repair, and, as long as the afterglow process was on, nailing did not occur. Once the afterglow time period was completed, that excess fuel caused the nailing I heard at idle...just food for thought. Good luck!!

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96 E300d

Your welcome, and I have to say, your saga regarding your trip would have caused me to loose the few strands of hair I have left in my head!!

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96 E300d

Yeah, I'm thinking the last thing I'll try ( after I get a proper inj side compression testor) is the DV valves. It actually leaks there now, whereas it did not before. Could be the increase in fuel pressure is exacerbating any leak.

It runs OK unless I accelerate, mid throttle, then the surging smoking begins. Doesnt matter if the flappers are on or not, its not the flappers. Almsot like too much fuel at part throttle. At WOT, it runs like a scalded ape.

Its not cleaning up like it used to at operating temp. Crappy running all the way around.

Well since the brace of DV's is now leaking somewhere....... If I had a qualified indy that knew these engines around here, I'd punt about now....